Ultrasonic is sound pressure with a frequency greater than 20 kHz. The characteristic of ultrasonic waves can be influenced by intensity, amplitude and frequency of oscillation. The other part of influence is an environment part which ultrasound used for transmission.

Ultrasonic energy can be sorted by the intensity on:

Active ultrasound – is created by the high-intensity (0.5 104 W/m²). It can be used for cleaning components, welding materials or medical therapy.

Passive ultrasound – is created by the lower intensity than active ultrasound. The specification for this type of energy is noninvasive characters in environment.

For autonomic mobile robotic system can be used the ultrasonic sensors with passive ultrasound energy.

2. Ultrasonic measure principle

Ultrasonic measuring is provided by non-contact measurement. Principle of distance measuring is based on the propagation time between the wave sent and the wave received. The difference between these times is used for determination distance. Ultrasonic measuring used two construction types:

source and sensor are separate

source and sensor are connected into the one device

3.Ultrasonic liquid level products

(1) The portable liquid level indicator is designed to measure the presence or absence of liquid at a certain height position in a container or in pipelines.The product is applicable to the detection of various types of liquids. Due to the technique of non-contact detection this liquid level indicator is an ideal choice for the detection of dangerous toxic or corrosive liquids.

(2) The External Ultrasonic Liquid Level control is a new type of liquid level monitoring and alarming instrument. The high frequency ultrasonic pulse produced by the probe of the liquid level control can pass through tank wall and transmit between the tank wall and the liquid and then be reflected back.

(3) The ultrasonic liquid level meter is designed to be mounted at the bottom of the tank ektexine without the need of drilling any holes on the tank so that easy assembly is, hence, realized and the measurement will not interrupt the normal operation of the liquid tank.